Liquid-fuel burner



. June 4, 1968 J. c. AIRTH ET AL 3,386,794

LIQUID-FUEL BURNER Filed May 17, 1966 2 Sheets-Sheet l In venlors JAMES C Amru #W LLIAM HFINDLAY mmqwlm, 9.29m

A ltorney;

June 4, 1968 J. c. AIRTH ET AL 3,386,794

- LIQUID-FUEL BURNER Filed May 17, 1966 2 Sheets-Sheet s In ventor;

JAMES C. Ami-H WiLLlAM HF'mol-Av ma gmmwfime A ttomeyg 3,336,794- LlQUlD-FUEL BURNER James C. Airth, Bishopbriggs, and William H. Findlay, Kiririntilloch, Scotland, assignors to James Howden & Company Limited Filed May 17, 1966, Ser. No. %,772 Claims priority, application Great Britain, June 8, 1965, 24,149/65 14 Claims. (ill. 431-415) ABSTRACT OF THE DKSCLGSURE A liquid-fuel burner includes a combustion chamber having a peripheral wall and a floor. Disposed at or near the floor of the combustion chamber is a double suction impeller having two side-by-side sets of blading namely a first set of blading to create a recirculatory flow of hot gas in the combustion chamber and through the blading and a second set of blading to create a flow of combustion air into the combustion chamber. In the combustion chamber is a rotary fuel distributor which is disposed so as to discharge fuel radially into the first set of blading into the combustion chamber towards the peripheral wall said blading atomizes the fuel and initially mixes same with the air and with hot gas after ignition. Fuel feed means are provided adapted to deliver fuel to the rotary fuel distributor.

This invention relates to a liquid-fuel burner of the kind having rotary fuel feed means adapted to create a fuel flow therethrough and discharge the fuel radially outwards into a combustion chamber, and rotary impeller means adapted to induce a flow of combustion air into the combustion chamber for admixture with the discharged fuel.

In a previously proposed burner of the aforesaid kind, the impeller means are of the double-suction type with top and bottom blading and are located at the bottom of a cylindrical wall enclosing a primary zone into which an upright rotary fuel feed means project and in which the initial igniting means are located, the arrangement being such that simultaneously with the flow of combustion air through the bottom impeller blading there is a flow through the top impeller blading of a mixture of hot gases and fuel, and both flows mingle in a secondary zone surrounding the primary zone. The provision of said primary zone entails some complication in the construction of the burner and also some disadvantage in the operation and servicing of the burner. For example, the overall height of the burner is considerable, and thermal distortion of the parts within the primary zone disturbs combustion. Moreover, in the event of ignition failure the fuel tends to be trapped in the hot central zone of the burner and an explosive noise is emitted.

The chief object of the present invention is to provide a liquid-fuel burner of the aforesaid kind which is of simple, compact construction.

According to the present invention a liquid-fuel burner comprises rotary impeller means adapted to create a flow of hot gas in the combustion chamber and a flow of combustion air into the combustion chamber, and rotary fuel feed means adapted to create a flow of fuel therethrough and discharge the fuel radially outwards at or near the impeller means into the hot-gas flow so that the fuel mixes with the hot gas.

Preferably the rotary impeller means consists of a horizontally disposed double-suction impeller having top and bottom blading respectively for hot gases and combustion air, and the fuel feed means are upright and at the upper end are adapted to discharge fuel radially 0utwards into the top blading.

States Pater Preferably also the burner includes electrical ignition means disposed at or near the top blading of the impeller to ignite the fuel/hot-gas mixture flowing from the top blading.

Thus, the cylindrical wall of the previous proposal may be dispensed with, thereby enabling simplification of the burner, including substantial reduction in the overall height, without substantial loss of efiiciency.

Moreover, in the event of ignition failure, the fuel is ejected radially outwards towards the periphery of the combustion chamber, so that the risk of explosive noise is avoided.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which FIG. 1 is a vertical sectional view of a motor-driver liquid-fuel burner, FIG. 2 is a fragmentary top plan view of the burner casing with the motor removed, and FIG. 3 is a fragmentary vertical sectional view showing a modification.

Referring to the drawings:

A burner for liquid fuel, e.g. paralfin oil, is detachably secured over a circular opening 2 in the floor 3 of an upright cylindrical combustion chamber. The burner has an upright tubular casing in two parts namely a smalldiameter part 4 tapered slightly downwards and a largediameter part 5 housed in the floor opening and detachably connected to the underface of the floor 3.

The casing 4 has centrally therein a cylindrical wall 6 upstanding from the floor 7 to define a cup 8 for fuel. Four equispaced radial webs 9 extend between the cas ing wall and the cup wall, and fuel is fed to the cup through a radial inlet duct 10 extending through the wall 6, the web 9 which is enlarged at 9A (FIG. 2) to accommodate the duct, and the wall 4. The floor 7 has therethrough a peripheral series of openings 11 permitting upward through-flow of combustion air, the openings being controlled by a valve member in the form of a hitand-miss rotary apertured disc 12. Within the cup 8, the floor 7 carries upstanding fuel feed means including a central cylindrical core 13 of hard-anodised aluminum having a bottom flange 14 secured to the floor by a screw 15 and having a helical groove 16 formed therein, and a rotary cylindrical sleeve 17 mounted on P.T.F.E.impregnated metal bearing rings 18 and 19 at the ends of the core, and spaced from and co-operable with the heical groove 16 to raise by viscous drag fuel admitted to the cup 8. The bottom of the parts 13, 17 is thus immersed in the fuel which serves to seal the bottom bearing and receive any leakage from the bottom bearing. An upward extension 17A of the sleeve 17 has secured concentrically therein, by a spring clip 25, a rotary fuel tube 20 having a frusto-conical bore 29A and having a base block 21 resting on a dry bearing disc 2 on top of the core 13. In the core 13, an annular groove 32, a radial passage 33, and an axial passage 34 together connect the top of the helical grove 16 with the bore of the rotary fuel tube 20. An O-ring 23 on the block 21 engages the internal wall of the extension 17A to seal the sleeves top bearings. The top of the fuel tube 20 has an outward horizonal flange 24 which serves as a dischar e wheel adapted to direct fuel radially outwards towards the wall of the combustion chamber, close to the floor 3 of said chamher. The floor opening 2 of the combustion chamber houses a double-inlet impeller 26 consisting of top and bottom sets of blades 27 and 28 on a rotor 29 secured to the fuel tube 20, the top set 27 projecting into the combustion chamber, and the fuel discharge wheel 24 directing fuel towards the upper zone of the top set, as indicated by full-line arrows. An annular baiiie plate 30 detachably mounted on said annular plate 5 surrounds the rotor 29 to direct combustion air radially outwards, and its outer periphery forms with the wall of the floor opening 2 and an annular slot 31 through which the combustion air passes upwards into the combustion chamber, as indicated by broken-line arrows. Initial ignition is effected by electrical ignition means consisting of a glow coil device with the coil 35 disposed close to a flamespreading ring 36 which surrounds the upper zone of the top set of impeller blades 27 and is thus horizontally aligned with the fuel discharge wheel 24. Rotation of the sleeve 17, fuel tube 20 and impeller 26 is effected by an electric motor 37 housed in the casing and having its rotor 38 secured to the sleeve 17 and its stator 39 supported on ledges 4d at the edges of the webs 9.

The outer end of the inlet duct it] is connectible by pipe to the main fuel-storage tank via a constantlevel reservoir to maintain the fuel at the level L in the cup 8.

In operation of the burner, with the glow coil 3 and motor 37 energized, combustion air is drawn upwards through the casing 4 to the eye of the bottom set of blades 28 and is discharged radially by the blades and flows upwards through the annular slot 31 into the combustion chamber, the airflow serving to cool the motor. Fuel is induced upwards along the helical groove 16 by the viscous drag created by the rotation of the sleeve 17 on the core 13, is lifted up the conical internal walls of the rotary fuel tube 20 by the vertical component of centrifugal force, and is sprayed radially outwards in a horizontal plane by the discharge wheel 24. The top set of blades 27 induces a flow of air downwards from the central zone of the combustion chamber into the radially directed stream of fuel, as indicated by the broken-line arrows, so that the fuel mixes with the air, the mixture strikes the ring 36 and is ignited by the glow coil 35, and the resultant flame spreads around the ring and passes outwards to meet the combustion air rising through the annular slot 31, whereupon mingling of the flows occurs and an annular flame pattern is established in the combustion chamber. Hot gas is then recirculated downwards from the combustion chamber, and radially outwards through the top set of blades 2'7 to mix with the fuel spray and vaporize same, so that efficient combustion is r created and maintained. The glow coil is then switched off.

The burner is very compact, being of low overall height, and is quickly and easily produced and readfly dismantled for servicing. Moreover, the explosive noise on ignition failure is avoided.

Again, the burner is relatively insensitive to variation in the fuel level in the cup 8, and to fuel-viscosity change due to ambient temperature variation. Also the burner 'is tamper-proof and gives repeatable and consistent liquid-output metering.

In the modification shown in FIG. 3, fuel is supplied to the bottom of the core-and-sleeve assembly 13, 17 through a valve consisting of an upright, waisted cylindrical plug 41 rotatably mounted in an upright cylindrical housing 42 formed by a central vertical bore in the core 13, an inlet duct 43 extending into the fuel cup 8 and also into the bottom of the housing 42 to supply fuel to the plug waist, an axial groove 44 in the plug head co-operable with an outlet opening 45 in the housing to permit full flow of fuel to the bottom of the annular space between core and sleeve, and a V-section groove is in the plug head extending peripherally from the axial groove and tapering to a point so that the size of the outlet opening is varied by rotation of the plug 41. The plug 41 may be rotated manually or by thermostat, and may be operatively coupled to the rotary apertured disc 12 so that the combustion-air supply is varied proportionately with the fuel supply.

We claim:

1. A liquidafuel burner comprising a combustion chamber having a peripheral wall and a floor, a double suction impeller within the combustion chamber at or near the floor of the combustion chamber and having two side-byside sets of blading namely a first set of blading to create a recirculatory fiow of air in the combustion chamber and through the blading and a second set of blading to create a flow therethrough of combustion air into the combustion chamber, a rotary fuel distributor in the combustion chamber disposed so as to discharge fuel radially outwards through the first set of blading and into the combustion chamber towards the peripheral wall whereby said blading atomizes the fuel and mixes same intimately with the air and with hot recirculatory gas following ignition, and fuel feed means adapted to deliver fuel to the rotary fuel distributor.

2.. The burner according to claim 1, including electrical ignition means disposed at or near the first set of blading of the impeller to ignite the fuel air mixture flowing from the binding, and consisting of a flame-spreading ring surrounding the outer blading of the impeller for impingement by fuel spray from the first set of blading, and a glow-coil device having the coil disposed close to the ring.

3. The burner according to claim ll, wherein the fuel feed means consists of a cylindrical core-and-sleeve assembly whereof the sleeve is rotatable and defines with the core a helical passage through which the fuel flows by viscous drag on rotation of the sleeve, fuel supply means delivering to the inner end of the assembly, a rotary tube at the outer end of and co-axial with the assembly and having a frusto-conical bore diverging outwardly and communicating at its inner end with the helical passage so that fuel from the helical passage flows along the conical walls by centrifugal force, and a wheel at the outer end of the tube to discharge fuel spray radially through the first set of blading.

i. The burner according to claim 3, wherein the discharge wheel is outwardly flanged at the outer end of the rotary tube.

5. The burner according to claim 3, wherein the fuel supply means consists of a constant-level fuel reservoir surrounding the inner end of the assembly to deliver fuel to the inner end of the helical passage.

6. The burner according to claim 3, wherein the fuel supply means includes a valve operable to adjust the amount of fuel delivered to the inner end of the helical passage.

7. The burner according to claim 3, wherein the impeller means, tube and sleeve together form a rotary unit.

8. A liquid fuel burner comprising a combustion chamber having a peripheral wall and a floor, a rotary impeller disposed within the combustion chamber at or near the floor of the combustion chamber and having blading to create a flow of combustion air into the combustion chamber, a rotary fuel distributor in the combustion chamber adapted to discharge fuel into the combustion chamber towards the peripheral wall, fuel feed means consisting of a cylindrical core-and-sleeve assembly whereof the sleeve is rotatable and defines with the core a helical passage through which the fuel flows by viscous drag on rotation of the sleeve, fuel supply means delivering to the bottom of the assembly, and a rotary tube at the outer end of and co-axial with the assembly for delivery of fuel from the helical passage onto the rotary fuel distributor, the impeller, tube and sleeve forming a rotary unit, a tapered tubular casing for throughflow of combustion air and with a large diameter portion surrounding the blading of the impeller; an electric motor mounted concentrically within a small-diameter portion of the tapered tubular casing with its rotor surrounding and connected to the sleeve of the assembly so that the motor drives the rotary unit, and an annular bafile plate mounted concentrically within the large-diameter portion to guide the radial flow of combustion air to the periphery of said portion for discharge therefrom axially into the combustion chamber.

h. The burner according to claim 8, wherein the rotary impeller consists of a horizontally disposed d0uble-suction impeller having top and bottom blading respectively to create a flow of air in the combustion chamber and a flow of combustion air into the combustion chamber, and the fuel feed means are upright, and the rotary fuel distributor is arranged at the upper end of the fuel feed means and is adapted to discharge fuel radially into the top blading for admixture initially with the air flowing through the top blading and with recirculatory hot gas following ignition, the large diameter portion surrounding the bottom blading.

10. The burner according to claim 9, including electrical ignition means disposed at or near the top blading of the impeller to ignite the fuel air mixture flowing from the top blading, and consisting of a flame-spreading ring surrounding the top blading of the impeller for impingement by fuel spray from the top blading, and a glow-coil device having the coil disposed close to the ring.

11. The burner according to claim 9, wherein the rotary fuel distributor consists of an outwardly turned flange at the outer end of the rotary tube.

12. The burner according to claim 9, wherein the fuel supply means consists of a constant-level reservoir surrounding the inner end of the assembly to deliver fuel to the inner end of the helical passage.

13. The burner according to claim 9, wherein the fuel References Cited UNITED STATES PATENTS 2,893,480 7/1959 McGillis et a1. 158-1 1,410,112 3/1922 Peirce 158-1 2,191,712 2/1940 Greenawalt 158-77 2,200,278 5/ 1940 Johnston 158-1 3,039,749 6/1962 Powell 15877 3,176,749 4/1965 Downs 1584 3,252,497 5/1966 McGillis 158-4 FREDERICK L. MATTESON, JR., Primary Examiner.

JAMES W. WESTHAVER, Examiner.

E. G. FAVORS, Assistant Examiner. 

